feat(system):优化后端

1.新增后端测试
2.增加了后端的加密
3.增加了i18n（国际化）

frontend/src/components/Auth/AuthPage.tsx

@@ -42,7 +42,7 @@ export function AuthPage({ onLoginSuccess }: AuthPageProps) {
       }
     } catch (err: any) {
       console.error(err);
-      setError(err.response?.data?.detail || err.response?.data?.message || 'Authentication failed');
+      setError(err.response?.data?.detail || err.response?.data?.message || t('auth.authFailed'));
     } finally {
       setLoading(false);
     }
@@ -89,7 +89,7 @@ export function AuthPage({ onLoginSuccess }: AuthPageProps) {
                   value={userName}
                   onChange={(e) => setUserName(e.target.value)}
                   className="w-full px-4 py-2.5 bg-bg-input border border-border-primary rounded-xl focus:outline-none focus:ring-2 focus:ring-accent/20 focus:border-accent transition-all text-text-primary placeholder:text-text-muted/60 text-sm"
-                  placeholder="Enter your username"
+                  placeholder={t('auth.usernamePlaceholder')}
                   required
                 />
               </div>
@@ -101,7 +101,7 @@ export function AuthPage({ onLoginSuccess }: AuthPageProps) {
                   value={password}
                   onChange={(e) => setPassword(e.target.value)}
                   className="w-full px-4 py-2.5 bg-bg-input border border-border-primary rounded-xl focus:outline-none focus:ring-2 focus:ring-accent/20 focus:border-accent transition-all text-text-primary placeholder:text-text-muted/60 text-sm"
-                  placeholder="Enter your password"
+                  placeholder={t('auth.passwordPlaceholder')}
                   required
                 />
               </div>
@@ -137,7 +137,7 @@ export function AuthPage({ onLoginSuccess }: AuthPageProps) {
           </div>
 
           <p className="text-center text-xs text-text-muted/60 mt-6">
-            KiloStar Distributed Multi-Agent System
+            {t('app.tagline')}
           </p>
         </div>
       </div>